Electron-beam tube as symbol-printing tube

ABSTRACT

An electron tube for the continuous translation of electrical data into characters of scanning pattern points to be reproduced on a fluorescent screen, preferably an ultraviolet screen, employs a raster structure of insulated metal strips which may be scanned to determine the data passing the raster structure in the form of electron beams. Cylindrical lenses are employed in the raster structure to overcome distortions at the edges of the picture.

United States Patent [191 Veith 1 Aug. 14, 1973 ELECTRON-BEAM TUBE ASSYMBOL-PRINTING TUBE [75] Inventor: Werner Veith, Munich 80, Germany[73] Assignee: Siemens Aktiengesellschait, Berlin and Munich, Germany[22] Filed: Sept. 16, 1070 [21] Appl. No.: 72,594

[30] Foreign Application Priority Data Sept. 23, 1969 Germany P 19 48153.9

[52] US. Cl. 315/31 R, 315/13 R, 315/21 R [51] Int. Cl. H01] 29/56 [58]Field of Search 315/13, 14,31, 31 TV [56] References Cited UNITED STATESPATENTS 3,331,985 7/1967 Hamann 315/13 2,939,982 6/1966 McNaney...315/14 2,826,716 3/1958 McNaney 315/13 3,501,673 3/1970 Compton 315/31 R3,040,205 6/1962 Walker 315/14 2,233,299 2/1941 Schlesinger... 315/143,092,746 6/1963 Smura 315/31 TV 2,383,751 8/1945 Spangenberg. 315/31 R2,967,969 I/ 1961 Stocker 315/31 TV Primary Examiner--Reuben EpsteinArrorneyl-1ill, Sherman, Meroni, Gross and Simpson [5 7] ABSTRACT Anelectron tube for the continuous translation of electrical data intocharacters of scanning pattern points to be reproduced on a fluorescentscreen, preferably an ultraviolet screen, employs a raster structure ofinsulated metal strips which may be scanned to determine the datapassing the raster structure in the form of electron beams. Cylindricallenses are employed in the raster structure to overcome distortions atthe edges of the picture.

4 Claims, 4 Drawing Figures PATENTEUAUB 14 ms IN VENTOR Werner Me/rh 8%@WATTYS.

, l ELECTRON-BEAM TUBE AS SYMBOL-PRINTING TUBE BACKGROUND OF THEINVENTION 1. Field of the Invention The invention relates to thecontinuous translation of electrical data into any kind of writtencharacters, symbols of such, which are to be reproduced on a fluorescentscreen for instance, arranged in lines and in particular to an electronray tube for such reproduction in which several electron rays arrangedin a plane can be deflected parallel and black and white scannedindividually or several together and which comprises among other thingsa ray producing system, a controllable ray forming arrangement (matrix,scanning pattern), a simple electron-optical acceleration lens, adeflecting system working for instance, magnetically and a collectingfluorescent screen (target).

2. Description of the Prior Art.

For the reproduction of texts and numerical values as they occur,especially with data processing machines and calculating machines, thereare required relatively fast electronic devices which work almostnoiselessly. The problem may be solved in many ways with the help ofelectron beams of electrical discharge tubes.

There has been known the writing of characters by means of a simplecathode ray tube in such a way that the electron beam carries out oneafter the other the lines, for instance, of a letter or of a number.Besides the fact that the selecting arrangement is quite complicated forcomplicated characters, the procedure requires relatively a large amountof time.

For another familiar tube, ready charaters are used in the tube where anelectron beam is faded out by letter and number patterns and isreproduced on the fluorescent screen. The process works very fast;however, the tube is complicated because the electron beam requires theprovision of a two-dimensional deflection arrangement'for its deflectionfrom the pattern. The electron beam must first pick out the desiredletter pattern for which the first deflection is required; then the beammust be guided back to the center of the tube and be projected on thepicture screen by a second deflecting arrangement. it is understandablethat the complicated deflection arrangement causes a degradation in thequality of the picture, especially at its edge. Moreover, only a limitednumber of characters can be utilized with such a tube.

Furthermore, there has been known the reproduction of the individualcharacter in form of scanning elements by the fading out of parts of thetotal electron ray by means of an aperture scanning pattern while theremainder similarly as for the reproduction of a television picture, isdirected over a certain part of the picture screen where the characteris to be reproduced. For this purpose, each aperture of the scanningpattern has an electrically conducting ring to which electrical signalsare applied from the outside by way of a line leading to it. Aside fromthe difficult realization of the lines, the steering of the electronbeam, for instance, for white scanning, is relatively costly since thewhite scanning takes place in form of individual time delays which mustbe very accurate.

It is the primary object of the present invention to avoid theabove-mentioneddifficulties and disadvantages.

There is also another problem. The types of tubes mentioned hereinbefore do have a reproduction system where the picture screen is at arelatively great distance from the electron lens so that generally anenlarged picture originates. However, in order to be able to put as manycharacters as possible on a given picture screen, small sharply designedcharacters are therefore required which can possibly be enlargedoptically; these characters are located outside the tube.

SUMMARY OF THE lNVENTlON For an electron beam tube according to thepresent invention especially for the continuous translating ofelectrical data into any kind of written characters, symbols or such,which are constructed of scanning points and are to be reproduced on afluorescent screen, for instance, arranged in lines means are providedto produce several electron rays arranged in a plane which can bedeflected parallel and can be black and white scanned individually, orseveral together, and which comprises among other things, a beamproducing system, a controllable ray forming arrangement (matrix,scanning pattern), a simple electron-optical acceleration lens, adeflecting system working, for instance, magnetically and a collectingfluorescent screen (target). The main objective of the invention issolved according to the invention by the fact that between thedeflection system and the collecting screen (target) there are arrangedat least two lenses forming a common electron-optical reproductionsystem in such a way, and that their focusses are dimensioned in such amanner, that the reproduction on the target obtained by them is reduced;and wherein two of these lenses arranged directly in front of the targetform a correcting system consisting of cylindrical lenses for correctingdistortions, especially at the corners of the picture.

The individual parallel electron beam bundles used here, which extendfrom the beam producing system, are arranged by the deflecting system tothe individual letters, written characters, or such in a line and thethus formed lines are transposed vertically one after the other. Herethe individual electron ray bundle enters, for instance, withconsiderable deflection slantingly into the space behind the deflectionsystem, i.e., into the range of the cylindrical lenses and consequentlyit experiences a more or less considerable distortion corresponding to aspherical aberration. The cylindrical lenses provided for theelimination of this blurredness comprise, in an especially advantageousmanner, a metal housing and in each case two metal strips placed thereelectrically separated. The metal housing is open toward the fluorescentscreen and has a large entrance aperture partition toward the beamproducing system. From the beginning, cylindrical lenses have a slightaberration and their tension can also be changed in order to balance theotherwise occurring reproduction faults in connection with thedeflection of the electron beam.

In front of the deflecting arrangement and the cylindrical lens systemarranged behind it, there is provided a beam forming arrangement for thedevelopment of an electron beam matrix which, in the simplest case,comprises electrodes arranged parallel to each other and formedprimarily of level metal sheets, such as the Wehnelt electrode, and ofanodes. These electrodes as well as their partial electrodes have anaperture raster (structure) which is the same for all pertainingelectrodes. Besides these electrodes, namely the first pull anode andthe main anode which together with the Wehnelt electrode form the firstacceleration lens, there is provided at a distance behind it in thedirection of the beam still another aperture scanning pattern with thesame arrangement of apertures but with smaller apertures, whichconstitutes in an especially advantageous manner the respective objectplane for the following acceleration lens. By means of small tubes, forinstance, made of metal, the apertures pertaining to each other arepreferably put at a distance from this additional aperture raster andfrom the main anode arranged in front of it. This measure has thepurpose that, by the formation of narrow channels, any slantinglyrunning electron beams especially can be registered on the collectingscreen. Only the electron beams getting through the fine openings of theaperture raster are used for further reproduction; here, the apertureraster itself functions as an object level for an electron-opticalsystem arranged therebehind. Such an inserted acceleration systemprevents the spreading of the electron rays and steers them furthermoreto a common spot of another reproduction system following behind. Theindividual lines of this reproduction system comprising two lenses arearranged with respect to each other in such a way, and are laid outregarding their focusses in such a way, that a reduced picture of theaperture raster originates on the fluorescent screen.

The aperture raster matrix or the aperture raster structure,respectively, of the individual electrodes belonging to the beam formingarrangement can have up to 20 X 30 circular holes; thereof the holescorresponding to each other of the electrodes or partial electrodesarranged one after the other coincide. In most cases, an aperture rastermatrix with about 5 X 7 holes is sufficient to reproduce letters,written characters or such of perhaps typewriter quality. For theselection of the points on the vertical lines and horizontal lines ofthe point matrix there is provided in an especially simple example ofdesign as the first pull anode a system of crossed, perforated anodebands which can be individually selected. These perforated sheet metalstrips, which are galvanically separated and have an electricalconnection toward the outside, are in each case arranged in two planesbehind each other according to the number of columns. The electronsemitted by a common cathode, which mostly has large surfaces and isproductive are first, by means of the Wehnelt electrode arranged infront of it, on the basis of its aperture raster structure subdividedinto a corresponding number of areas. Thereupon, a selection for theparticular columns, for instance for the vertical lines, takes place ineach case by means of the individually selectable perforated strips ofthe partial anode arranged in the formost plane. By means of the secondperforated band group behind it, the introduced electron beam course, isso-to-speak allowed belatedly, or is entirely prevented. The electrodearrangement as well as the execution of the black and white scan, isespecially simple with this form of electron beam since for eachperforated band of the anode there is needed only one electricalconnection from outside. However, this method has one disadvantage whichconsists thereof that not all points can really be selectedsimultaneously or black and white scanned, respectively.

In an advantageous further development, the cathode is divided into anumber of individual cathodes corresponding to the point scanningpattern. Each of these individual cathodes has a separate line fromoutside by way of which in each case the potential of the individualcathode, with respect to the common Wehnelt electrode, can be raised orlowered. In this case a subdivision of the anodes into perforated stripsis not required but in place of it perforated metal sheets are provided,so-to-speak, in one piece.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantagesof the invention will be explained below with the aid of drawingexamples of the described electron ray tube. Parts, which do notabsolutely contribute to the understanding of the invention, have beenomitted from the drawings or have been left unmarked. In the drawings:

FIG. I shows a schematic picture of the electrode arrangement and of theelectron beam course, especially in the case of a common cathode;

FIG. 2 shows the production system for simultaneous scanning withseparate cathodes;

FIG. 3 shows schematically a possible technical design example of a tuberegarding the electron formation and arrangement; and

FIG. 4 shows the scanning pattern of the number 3" as an example of thepossible formation of the numbers and characters to be reproduced.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, there is marked by 1a common cathode which must be designed with especially large surfacesand must beproductive. Before it, there is arranged the Wehneltelectrode 2, which is already designed as an aperture raster and beforewhich there is arranged again the first pull anode 3 and 4 consisting ofcrossed anode bands. The size of the point raster on which theseelectrodes are based can vary, for instance, between 7 X 5 and 20 X 30picture points. Experience has shown that, for the writing of letters ofa good typewriter quality, the aperture arrangement mentioned last is byfar sufficient.

The crossed aperture bands 3 and 4, separated electrically from eachother, serve as the electrodes of the first pull anode in order toselect the points on the vertical and horizontal lines of the pointmatrix. They can be selected individually and thus provide the selectionfor one column, for instance, a vertical line. Thus a positive voltageof only a few volts, for instance of 10 to 50 volts, is sufficient toobtain, with a distance of a few tenths, of a millimeter, a current ofthe magnitude of lmA per picture point. The second row of anode bands 4of a similar form is arranged in the beam direction behind the group ofanode bands 3 described before. In FIG. 1, the bands run parallel to thecharacter plane. By putting a positive voltage on these anode bands 4,the ray passage achieved by the first anode bands 3 is delayed; while bythe application of a small negative voltage of only a few volts belowzero (cathode potential) the passage of the beam is prohibited. By thismeasure it is possible to select individual points of the scanumn onlythe 2nd and 9th row are opened and this is done immediately. The exampleof the design shows that point rasters with less than 20 X 30 pointsalready make possible sufficiently clearly recognizable numbers.However, with this steering technique of the anode bands not every pointcan be selected simulta neously as it can be done by means of thefurther development shown separately in FIG. 2.

Following the anode bands 4, there is a plate 5 as the main anode, forinstance, a square plate which, according to the scanning patternselected in connection with the Wehnelt electrode and the first pullanode, is provided, for instance, with 5 X 7 35 circular holes and whichare made to coincide with the openings of the anode bands 3 and 4.Between the anode bands 4 and the main anode 5, lenses develop duringoperation which focus the electron beams, which pass through the holes,on very small openings in the aperture raster plate 6 arranged at adistance behind. The electrodes 5 and 6 can be connected by small tubesin such a way that channels are formed between the holes correspondingtp each other of the two electrodes. With these small tubes 15, forinstance made of metal, it is intended that slantingly running electrodebeams cannot be registered during the reproduction. The focussedelectron beams passing vertically through the fine openings of theaperture raster plate 6 are used for further reproduction in such a waythat the electrode 6 itself functions as the object plane for afollowing electron-optical lens 7. Such a lens 7, for instance, in theform of an acceleration lens, prevents namely the spreading of theelectron beams and furthermore steers the 5 X 7 35 individual beams to acommon spot of the following lens system 8. Lens 7 and lens system 8,both are arranged with respect to each other in such a way and theirfocusses together are laid out in such a way that a reduced picture ofthe aperture raster of plate 5 appears on the fluorescent screen(target) 9.

While the lens 7 can be a simple acceleration lens as it is common forelectron beam systems, the lens system 8 consists of twoelectron-optical cylindrical lenses. Between lens 7 and the lens system8, there is the deflecting system 10 which, for instance, worksmagnetically. It serves to arrange the individual letters, numbers orsuch in a line and thereupon to move the individual lines vertically oneafter the other. For this reason the deflecting angle of the deflectingsystem must be relatively large and therefore it is again required thatthe diameter of the lens system 8 is very much larger than the diameterof the diaphragm electrodes 3, 4, 5 and 6 as well as of lens 7.

By means of the especially favorable electrode arrangement shown in FIG.2, it is possible, in contrast to the arrangement described before, toselect each individual point of the point screen. For this purpose thereis provided a number of individual cathodes ll corresponding to thenumber of scanning pattern points. Each of these individual cathodes hasa separate line from outside by way of which for the purpose of blackand white scanning the respective potential can be raised orlowered. Apartition of the partial electrodes of the first pull anode intoso-called crossing anode bands is not required. In place of it, there isprovided in each case only a single massive aperture plate 5 asan anode.The other electrodes following it are the same ones as described beforein FIG. 1.

FIG. 3 shows a picture of the described tube, approximately correct asto scale, where, however, deviating from the lower part, the electrodes1 to 7 from the schematic sketch in FIG. 1 are drawn at a much smallerscale. The same is true also for the deflection system 110.

After leaving the deflecting system 10, the respective electron beambundle 20 enters slantingly, fo instance, with considerable deviation,on its further course the space in which the cylindrical lenses areplaced. To this system of cylindrical lenses, there belongs inparticular the metal tube casing (housing) 12 and two bandshaped metalbars 13 and 14 arranged therein vertically to each other. Thecylindrical lenses are necessary be cause the unavoidable sphericalaberration of a normal lens would cause considerable blurredness in thepicture edge. Cylindrical lenses, on the other hand, have from the startless spherical aberration and their tension can also be changed in orderto make up for the reproduction errors in connection the deflection ofthe electron beam in dependence of the deflection voltage in order tothereby provide dynamic focussing. While the housing 12 is on a highpositive potential of abour 10 kV, the potential of the bands 13 and 14,for instance, for the central beam bundle, must assume values in therange of about 0 volts, referring to the cathode. With steering of theelectron beam into one of the corners of the housing which is forinstance, square, both band pairs 13 and 14 are then switched to apositive potential in order to give a weaker refractive power to theindividual lines forming in each case between the housing 12 and thebands 13 or 1 4. Thus the tube works with dynamic focussing, i.e., theelectric potential or the voltage of the electrodes of the individuallenses l3 and 14 is changed according to the steering of the electronbeam.

The described tube is intended, for instance, for the reproduction ofwritten characters within the framework of a document of the size of atypewritten page. But it can also be converted relatively easily into atube for non-mechanical printing. in this case only one line is neededso that the deflecting system for the entire range of the fluorescentscreen is simplified. Such a printer thus works as series or lineprinter by using the advancing of the provided paper feeder 16 for thewriting of additional lines. Since the character appears first only onthe fluorescent screen (target) 9, light sensitive paper is preferablyused in this case. Such paper, as it is generally obtainable today in asatisfactory quality, however, works especially with ultraviolet light.For this reason, a UV phosphorus as well as a UV transparent front glassplate must be provided for the printer. Here, however, the front glassplate 9 has merely the form and size of a single line. A normal sizeletter is advantageously chosen, i.e., approximately 2.5 to 3 mm high,and the light sensitive paper is brought into direct contact with thefront plate. if an additional reproducing optical system is used, a loss:of light must be accepted but, on the other hand, it has the quiteconsiderable advantage that the size of the letters can be selectedabout as desired thus, for instance, it can be enlarged to a desiredsize or also reduced accordingly for microfilms.

Another alternative for the character writing tube consists thereof thatthe horizontal deflection of the entire beam bundle is also used for thewriting of the letters. in such a case, only one column of points whichare vertical one above the other, is needed. While the electron beam ofa line runs horizontally over the picture screen, the respective 7 or 30points of a vertical column are during the advancing of the deflectedswitched black and white, as desired, automatically by the width of onepicture point. In this manner, there originates a character writing tubewith the same writing speed as described before, but with a considerablysimpler construction. It has a special significance always where it isimportant to write a continuous text where the deflection speed of anelectron beam bundle is constant. In this sense the same arrangement isvalid also for the use of the described tube as a printer.

Essential advantages of the described tube in comparison to other tubesconsist thereof that, for the composition of the characters from a pointraster, there is used a matrix of electron beams which either originatefrom a common cathode and are black and white scanned by the use ofcrossed anode bands or which originate from a corresponding number ofindividual cathodes which themselves are black and white scanned. Thepoints required in each case are simultaneously written by theseelectron beams. With the possibility of a reducing reproduction, everydesired character thus also Greek and Arabic letters can be reproducedmerely by a change of the selecting sytems located outside of the tubeand drawings with curves with different line marking can be presented.

Many changes and modifications may be made in my invention by oneskilled in the art, and I intend to include in the patent warrantedhereon, all such changes and modifications that may reasonably andproperly be included within the scope of my contribution to the art.

I claim:

1. An electron beam tube for continuous conversion of electrical datasignals into characters, symbols or the like composed of scanningpattern points arranged in lines and to be reproduced on a fluorescenttarget, comprising: cathode means for providing a plurality of parallelelectron beams; a controllable beam forming arrangement disposedadjacent said electron beams; an electron-optical acceleration lensdisposed adjacent said controllable beam forming arrangement; a beamdeflecting system disposed adjacent said electronoptical accelerationlens; a plurality of lenses disposed between said deflecting system andsaid target having focal lengths dimensioned to provide a reduced imageupon said target, said plurality of lenses including a pair ofcylindrical abberation correcting lenses disposed directly adjacent saidtarget for efi'ecting distortion correction; and a cylindrical metalhousing having an open end directed toward said target and a largeaperture directed toward said deflecting system, said pair ofcylindrical lenses disposed within said housing and each consisting of ametal strip electrically isolated from the other.

2. An electron beam tube according to claim 1, wherein said metalhousing is connected to a high potential of about 10 kV, and comprisingmeans for applying approximately the same potential to said cathode andto said metal strips and changing the potentials so applied to providedynamic focusing.

3. An electron beam tube for continuous conversion of electrical datasignals into characters, symbols or the like composed of scanningpattern points arranged in lines and to be reproduced on a fluorescenttarget, comprising: cathode means for providing a plurality of parallelelectron beams; a controllable beam forming arrangement disposedadjacent said controllable beam electron beams; an electron-opticalacceleration lens disposed adjacent said controllable beam a beamdeflecting system disposed adjacent said electron-optical accelerationlens; and a plurality of lenses disposed between said deflecting systemand said target and having focal lengths dimensioned to provide areduced image upon said target, said plurality of lenses including apair of cylindrical abberation correcting lenses disposed directlyadjacent said target for effecting distortion correction, said beamforming arrangement corresponding to an electron beam matrix andincluding electrodes arranged parallel to each other and each comprisingflat metal sheets, each of said sheets including a plurality of holestherein to form the same aperture raster matrix, the aperture rastermatrix consisting of up to 20 X 30 holes with the holes of each sheetbeing aligned with the holes of the other such sheets.

4. An electron beam for continuous conversion of electrical data signalsinto characters, symbols or the like composed of scanning pattern pointsarranged in lines and to be reproduced on a fluorescent target,comprising: cathode means for providing a plurality of parallel electronbeams; a controllable beam forming arrangement disposed adjacent saidelectron beams; an electron-optical acceleration lens disposed adjacentsaid controllable beam forming arrangement; a beam deflecting systemdisposed adjacent said electronoptical acceleration lens; and aplurality of lenses disposed between said deflecting system and saidtarget and having focal lengths dimensioned to provide a reduced imageupon said target, said plurality of lenses including a pair ofcylindrical abberation correcting lenses disposed directly adjacent saidtarget for effecting distortion correction, said cathode means includinga plurality of cathodes each operable to provide a separate electronbeam and each including a respective line for receiving a respectivescanning potential.

1. An electron beam tube for continuous conversion of electrical datasiGnals into characters, symbols or the like composed of scanningpattern points arranged in lines and to be reproduced on a fluorescenttarget, comprising: cathode means for providing a plurality of parallelelectron beams; a controllable beam forming arrangement disposedadjacent said electron beams; an electronoptical acceleration lensdisposed adjacent said controllable beam forming arrangement; a beamdeflecting system disposed adjacent said electron-optical accelerationlens; a plurality of lenses disposed between said deflecting system andsaid target having focal lengths dimensioned to provide a reduced imageupon said target, said plurality of lenses including a pair ofcylindrical abberation correcting lenses disposed directly adjacent saidtarget for effecting distortion correction; and a cylindrical metalhousing having an open end directed toward said target and a largeaperture directed toward said deflecting system, said pair ofcylindrical lenses disposed within said housing and each consisting of ametal strip electrically isolated from the other.
 2. An electron beamtube according to claim 1, wherein said metal housing is connected to ahigh potential of about 10 kV, and comprising means for applyingapproximately the same potential to said cathode and to said metalstrips and changing the potentials so applied to provide dynamicfocusing.
 3. An electron beam tube for continuous conversion ofelectrical data signals into characters, symbols or the like composed ofscanning pattern points arranged in lines and to be reproduced on afluorescent target, comprising: cathode means for providing a pluralityof parallel electron beams; a controllable beam forming arrangementdisposed adjacent said controllable beam electron beams; anelectron-optical acceleration lens disposed adjacent said controllablebeam a beam deflecting system disposed adjacent said electron-opticalacceleration lens; and a plurality of lenses disposed between saiddeflecting system and said target and having focal lengths dimensionedto provide a reduced image upon said target, said plurality of lensesincluding a pair of cylindrical abberation correcting lenses disposeddirectly adjacent said target for effecting distortion correction, saidbeam forming arrangement corresponding to an electron beam matrix andincluding electrodes arranged parallel to each other and each comprisingflat metal sheets, each of said sheets including a plurality of holestherein to form the same aperture raster matrix, the aperture rastermatrix consisting of up to 20 X 30 holes with the holes of each sheetbeing aligned with the holes of the other such sheets.
 4. An electronbeam for continuous conversion of electrical data signals intocharacters, symbols or the like composed of scanning pattern pointsarranged in lines and to be reproduced on a fluorescent target,comprising: cathode means for providing a plurality of parallel electronbeams; a controllable beam forming arrangement disposed adjacent saidelectron beams; an electron-optical acceleration lens disposed adjacentsaid controllable beam forming arrangement; a beam deflecting systemdisposed adjacent said electron-optical acceleration lens; and aplurality of lenses disposed between said deflecting system and saidtarget and having focal lengths dimensioned to provide a reduced imageupon said target, said plurality of lenses including a pair ofcylindrical abberation correcting lenses disposed directly adjacent saidtarget for effecting distortion correction, said cathode means includinga plurality of cathodes each operable to provide a separate electronbeam and each including a respective line for receiving a respectivescanning potential.